qasn1element: add QAsn1Element::toInteger

This change adds the ability to decode ASN.1 INTEGER fields,
provided they represent a positive number of less than 64-bit.

This is needed for PKCS#12 decoding.

Change-Id: Iafb76f22383278d6773b9e879a8f3ef43c8d2c8f
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>

src/network/ssl/qasn1element.cpp

@@ -242,6 +242,30 @@ QMultiMap<QByteArray, QString> QAsn1Element::toInfo() const
     return info;
 }
 
+qint64 QAsn1Element::toInteger(bool *ok) const
+{
+    if (mType != QAsn1Element::IntegerType || mValue.isEmpty()) {
+        if (ok)
+            *ok = false;
+        return 0;
+    }
+
+    // NOTE: negative numbers are not handled
+    if (mValue.at(0) & 0x80) {
+        if (ok)
+            *ok = false;
+        return 0;
+    }
+
+    qint64 value = mValue.at(0) & 0x7f;
+    for (int i = 1; i < mValue.size(); ++i)
+        value = (value << 8) | quint8(mValue.at(i));
+
+    if (ok)
+        *ok = true;
+    return value;
+}
+
 QVector<QAsn1Element> QAsn1Element::toVector() const
 {
     QVector<QAsn1Element> items;

src/network/ssl/qasn1element_p.h

@@ -97,6 +97,7 @@ public:
 
     QDateTime toDateTime() const;
     QMultiMap<QByteArray, QString> toInfo() const;
+    qint64 toInteger(bool *ok = 0) const;
     QVector<QAsn1Element> toVector() const;
     QByteArray toObjectId() const;
     QByteArray toObjectName() const;

tests/auto/network/ssl/qasn1element/tst_qasn1element.cpp

@@ -122,6 +122,14 @@ void tst_QAsn1Element::integer()
     QFETCH(QByteArray, encoded);
     QFETCH(int, value);
 
+    // read
+    bool ok;
+    QAsn1Element elem;
+    QVERIFY(elem.read(encoded));
+    QCOMPARE(elem.type(), quint8(QAsn1Element::IntegerType));
+    QCOMPARE(elem.toInteger(&ok), value);
+    QVERIFY(ok);
+
     // write
     QByteArray buffer;
     QDataStream stream(&buffer, QIODevice::WriteOnly);